It is, I can spot that Tuxedo grain vinyl a mile away… Actually formally called “CADILLAC SMALL TUXEDO GRAIN”

76-79 Seville used Tuxedo. 1980-on Cadillacs predominately used Elk which became the standard for most GM cars at that time. Especially for heavily padded versions.

An additional factoid, Sevilles were all vinyl roofed in the early days because the unique for Seville cap on the X platform covered the welding. Later, they were able to engineer a smooth transition for the cap allowing the offering of a non vinyl model.